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United States Department of Agriculture

Agricultural Research Service

Title: Prion Genetics and Susceptibility to Scrapie in Suffolk Sheep in the United States

Author
item O'Rourke, Katherine

Submitted to: United States Animal Health Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 6, 1996
Publication Date: N/A

Interpretive Summary: Scrapie is a fatal neurodegenerative disease of sheep and goats. Polymorphism¿s in the prion gene are associated with susceptibility to disease in several breeds of sheep in Europe. We report the association of a single prion genotype (136-AA, 171-QQ) in 30/30 scrapie affected Suffolk sheep. This genotype was found in 56.5% of the normal, unaffected sheep sampled (n=565). In an allied study, Suffolk sheep were experimentally inoculated with the scrapie agent by the oral route. 60% (63/105) sheep developed disease. All affected sheep carried the 136-AA, 171-QQ genotype. Sheep with the genotypes 136-AA, 171-QR and 136-AA, 171-RR remained disease free for periods up to 10 years. This study suggests that selection of breeding stock carrying the 171-R gene will reduce the incidence of clinical scrapie in Suffolk sheep.

Technical Abstract: Genetic analysis of the prion gene was performed to determine the association of sheep scrapie with susceptibility to experimental and natural scrapie in U.S. Suffolk sheep. 30/30 Suffolk sheep with natural scrapie were homozygous for 136-Alanine, 171-glutamine. This genotype was found in approximately 56% of a sample of 545 unaffected sheep. 105 Suffolk sheep were experimentally inoculated by the oral route with the scrapie agent. 60% (63/105) sheep developed scrapie. All 63 were homozygous for 136-AA, 171-QQ. 24/24 sheep heterozygous at codon 171 (171- QR) and 5/5 sheep homozygous for arginine at codon 171 (171-RR) remained disease free for periods as long as 10 years. These studies demonstrate that 171-QQ is the major susceptibility genotype of Suffolk sheep in the U.S.

Last Modified: 7/24/2014
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